Usually, a terminal for connection to a semiconductor chip (hereinafter referred to as a connecting terminal) is formed on a principal surface (front face) of a wiring board. Nowadays, the density of the connecting terminals has been becoming high, and therefore the distance (pitch) of the arranged connecting terminals has been narrow. In view of this, a wiring board adopting a Non-Solder Mask Defined (NSMD) shape where a plurality of connecting terminals is disposed in the same opening of a solder resist has been proposed.
However, in the ease where the plurality of connecting terminals are disposed at narrow pitches in the same opening, a solder coated on the surface of the connecting terminal possibly flows out to adjacent connecting terminals, resulting in a short between the connecting terminals. Since the connecting terminals are disposed at high density, the wiring widths of the connecting terminals become narrow. Accordingly, there is a possibility that the connecting terminals cannot obtain sufficient adhesion strength. In this case, the connecting terminal may be fallen over or peeled of under fabrication process.
Therefore, filling up between each connecting terminal with an insulating solder resist has been proposed (see, for example, Patent Document 1). With the method, since the solder resist is filled up between the connecting terminals, outflow of the solder coated on the surface of the connecting terminal to the neighboring connecting terminals is reduced. Since the side surface of the connecting terminal contacts the solder resist, the connecting terminal that is fallen over or peeled off is reduced.